Rigid non-transparent photoluminescent floor material

ABSTRACT

A rigid, non-transparent photoluminescent tile having photoluminescent material exposed on a top surface of the tile, wherein the photoluminescent material, including photoluminescent particles and chips, illuminates when the ambient light is removed.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S.application Ser. No. 10/271,243 entitled “Photoluminescent Floor Tile”,filed on Oct. 15, 2002, now allowed, which claims priority to U.S.patent application Ser. No. 10/147,740 entitled “Photoluminescent FloorTile”, filed on May 16, 2002, now allowed, which applications areincorporated herein by references in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is related to rigid non-transparent photoluminescentflooring material. In particular, the invention relates to floor tileshaving light-emitting wear layers that illuminate when the ambient lightis removed.

2. Description of the Related Art

Buildings are provided with emergency signs marking exits and fireescape routes. These signs direct persons out of the building in theevent of an emergency. Because the electric service is likely to be lostduring an emergency, the emergency signs tend to be powered by anemergency backup system which typically include batteries andgenerators. Additionally, emergency lights are required in certainbuildings to provide illumination for the evacuees. These emergencylights are also powered by backup batteries and generators.

The emergency backup system that powers lights and emergency signs hasdisadvantages. The backup lighting system must provide coverage for allescape routes. Extensive coverage can lead to costly installation.Moreover, maintenance of the emergency backup system is critical inensuring reliable performance during an emergency. Accordingly, althoughthe emergency events are infrequent, routine maintenance of the backupsystem is necessary.

Because of these disadvantages, emergency lighting systems that do notrely on power have been developed to supplement powered backup system.One type of the non-powered system employs photoluminescent material toprovide the light. Photoluminescent material absorbs lights from ambientsources. The absorbed photon energy is readily released, often at aparticular wavelength. The photoluminescent light emitted can beparticularly bright in the dark, which makes the material a goodcandidate for providing a non-powered backup system to mark theemergency exits and escape routes. Some of the photoluminescentmaterials are so efficient in storing and releasing the photon energy,they are capable of emitting light for hours after the ambient light hasbeen removed.

Flexible sheets or mats are among the most common material into whichphotoluminescent material can be distributed and fused. Thephotoluminescent sheets and mats are typically affixed to a surface,such as a floor or walls, which will light up and provide illuminationin the dark. The installation is often labor intensive due to theadditional step of affixing the light-emitting material to an existingfloor or walls. It further requires special treatment of the surfaces toensure a failsafe affixation. Often, these sheets and mats do notprovide a pleasing appearance under normal light.

Another type of building material that illuminates in the dark isdisclosed in U.S. Pat. No. 6,309,562 by Sakai. Sakai discloses anartificial stone incorporating a small amount of photoluminescentmaterial into largely transparent inorganic aggregates, such as silica.The photoluminescent material is expected to illuminate through theentire thickness of the artificial stone due to the transparency of thestone.

SUMMARY OF THE INVENTION

The present invention provides a rigid, photoluminescent tile thatilluminates when the ambient light is removed. In particular, thephotoluminescent tile comprises a tile base having a top surface, athermoplastic binder system within said tile base, the thermoplasticbinder system being 5-50 wt % of the total weight of the tile, anon-transparent inorganic filler within said tile base; and aphotoluminescent material within the tile base and being exposed on saidtop surface of said tile base, wherein the combined weight of theinorganic filler and the photoluminescent material is 50-95 wt % of thetotal weight of the tile. The photoluminescent material can bephotoluminescent particles or chips.

In a further embodiment, the present invention provides aphotoluminescent tile having a non-photoluminescent substrate bondedwith a wear layer. The wear layer has a top surface and a bottom surfaceand includes a thermoplastic binder system within said wear layer, saidthermoplastic binder system being about 5-50 wt % of the total weight ofthe wear layer; a non-transparent inorganic filler within said wearlayer, a photoluminescent material within said wear layer and beingexposed on the top surface of said wear layer, wherein the combinedweight of the inorganic filler and the photoluminescent material isabout 50-95 wt % of the total weight of the wear layer. Thephotoluminescent material can be photoluminescent particles or chips.

The present invention further provides a floor comprise a plurality ofthe photoluminescent tile according to the various embodiments of theinvention and a plurality of non-photoluminescent tiles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a floor tile in accordance with one embodimentof the present invention, in which photoluminescent particles are evenlydistributed throughout the entire body of the tile.

FIG. 2 is a sectional view of the floor tile shown in FIG. 1.

FIG. 3 is a enlarged view of a portion of the tile shown in FIGS. 1-2.

FIG. 4 a is a top view of a floor tile in accordance with anotherembodiment of the present invention, in which photoluminescent chips aredistributed in a non-photoluminescent tile base.

FIG. 4 b is a top view of a floor tile in accordance with yet anotherembodiment of the present invention, in which photoluminescent chips aredistributed in a non-photoluminescent tile base.

FIG. 5 is a top view of a floor arrangement comprising a plurality ofphotoluminescent tiles and non-photoluminescent tiles.

FIG. 6 is a top view of a floor arrangement comprising a plurality ofphotoluminescent tiles and non-photoluminescent tiles.

FIG. 7 is a sectional view of a floor tile in accordance with yetanother embodiment of the present invention, in which a photoluminescentwear layer having photoluminescent particles overlies anon-photoluminescent tile base.

FIG. 8 is a sectional view of a floor tile in accordance with yetanother embodiment of the present invention, in which a photoluminescentwear layer having photoluminescent chips overlies a non-photoluminescenttile base.

FIG. 9 is a sectional view of a floor tile in accordance with yetanother embodiment of the present invention, in which photoluminescentparticles are embedded near the surface of a non-photoluminescent tilebase.

FIG. 10 is a sectional view of a floor tile in accordance with yetanother embodiment of the present invention, in which photoluminescentchips are embedded near the surface of a non-photoluminescent tile base.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Photoluminescent Tiles having Photoluminescent Material Throughout theTile Base

The present invention provides a rigid, non-transparent buildingmaterial that incorporate photoluminescent material, including particlesor chips of material having photoluminescent particles in the chips. Thebuilding material is durable and provides long-lasting illumination whenthe ambient light is removed. While the building material of the presentinvention can be manufactured in a variety of shapes and dimensions, itis preferred that the material be formed into tiles for easyinstallation as flooring or wall material.

FIGS. 1-3 show one embodiment of the present invention whereinphotoluminescent particles 16 are disbursed throughout a tile base 18 toprovide a photoluminescent tile 10. The portion of the photoluminescentparticles present on the top surface 12 of the photoluminescent tile 10is attributable for absorbing and storing the light from and foremitting luminescence to the ambient environment.

As used herein, “tile base” or “tile base composition” refers to anon-photoluminescent tile composition into which a photoluminescentmaterial, including particles or chips can be incorporated. The tilebase typically comprises an inorganic filler and an thermoplastic bindersystem. “Inorganic filler” refers to a non-transparent mineral material.Typically, the inorganic filler can be crushed or ground limestone orground clay. Generally speaking, the amount of the inorganic filler isat least half or a substantial portion of the total weight of the tilebase to impart the necessary rigidity.

“Thermoplastic binder system”, also referred as the “vinyl resins”,refers to a largely organic composition including resins, plasticizerand stablizer. The thermoplastic binder system can be softened andmelted at high temperature and cooled down to harden. At the moltenstage, the binder system can be mixed thoroughly with the inorganicfiller and/or photoluminescent material. The malleable mixture can thenbe processed, rolled or calendared. While cooling down, the mixturehardens and fuses together. Due to the thermoplastic nature of thebinder system, the above process can be repeated infinitely withoutsubstantially affecting the material property of the binder. As will bediscussed below in more details, the thermo-reversibility of thethermoplastic binder thus enables the recycling of the defective orbroken tiles by re-incorporating them into a later batch of the tileproduction.

Suitable resins for the binder system include polyvinyl chloride (PVC)homopolymer, polyvinyl chloride/poly vinyl acetate (PVA) copolymer or amixture thereof. The molecular weights of the polymer components aretypically in the range of 55-60K Dalton. Compared to the PVC/PVAcopolymer, PVC homopolymer is generally regarded by one skilled in theart as being tougher which provides the impact resistance. The PVC/PVAcopolymer, on the other hand, processes better and fuses at lowertemperature. It is therefore preferred to use a mixture of the PVChomopolymer and PVC/PVA copolymer in order to exploit their respectivecharacteristics and optimize the products' processing and physicalproperties. Typically, the mixture comprises low molecular weight PVChomopolymer (55-58K) and high molecular weight PVC/PVA copolymer(58-60K).

As used herein, “plasticizer” refers to a type of chemicals that modifythe crystalline and often brittle vinyl resins by making them moreplastic or flexible. Plastizers work by increasing the free volumeavailable to the polymer chain segments which increases the rotationaland translational motion of the resin chains. In addition, theplasticizers reduce the polymer to polymer interactive forces therebymaking the polymeric chains more flexible. For purpose of thisinvention, phthlate plasticizers, including butylbenyzylphthalate (BBPor S-160), and diisononylphthalate (DINP) maybe be used.

As noted above, in order to obtain a rigid tile base, the inorganicfiller accounts for about 50-95 wt % of the total weight of the tilebase, whereas the thermoplastic binder system accounts for 5-50 wt % ofthe total weight of the tile base. As a general rule, the more inorganicfiller is incorporated, the more rigid and brittle the finished tilebase is, and the more difficult it is to process. Conversely, the morethermoplastic binder system, the less rigid the tile base is and theeasier to process. Generally speaking, the inorganic filler amounts to50-95 wt % of the total weight of the tile base. More typically, theinorganic filler is 60-90 wt % of the total weight of the tile base.Even more typically, the inorganic filler is 70-85 wt % of the totalweight of the tile base.

The non-photoluminescent tile base composition as described above issometimes referred as “Vinyl Composition Tiles” (VCT) in the tilemanufacturing industry.

The “photoluminescent material”, as used herein, refers tophotoluminescent particles or photoluminescent chips.

“Photoluminescent particles”, as used herein, refer to non-radioactivephotoluminescent pigment. One suitable pigment comprises rare earthmaterials. These photoluminescent pigments are each characterized by lowtoxicity, short excitation time, high brightness and long illuminatinglife. One example of a suitable pigment is strontium aluminate having aeuropium activator. It is commercially available in different colors asSeries G-200, Y-200, B-200 or V-200 from Way2glo, Inc., Thousand Oaks,Calif.

The photoluminescent particles of the present invention are fine powderswith average dimension of about 30 μm. Thus, in the first embodiment ofthe present invention, photoluminescent particles are mixed thoroughlywith the inorganic filler and thermoplastic binder system to provide aphotoluminescent tile 10.

Because the photoluminescent particles are inorganic materialthemselves, the combined weight of the particles and inorganic fillerscan comprise between 50-95 wt % of the total weight of the tile 10 inorder to form a rigid glowing tile. More typically, the combined weightof the particles and the inorganic filler is 60-90 wt % of the totalweight of the tile base. Even more typically, the combined weight of theparticles and the inorganic filler is 70-85 wt % of the total weight ofthe tile base.

The amount of the photoluminescent particles in the tile 10 determinesthe brightness and duration of the photoluminescence emitted from thetile. Typically, in order for the tile to have sufficient amount of theparticles to give off a visible illumination in the dark, at least 10 wt% of the total weight of tile 10 is consisted of the photoluminescentparticles. The amount of the photoluminescent material can go up to 90wt % of the total weight of the tile 10. Economic considerations,however, may dictate that between 15-40 wt % of the photoluminescentparticles can be incorporated to ensure a satisfactory brightness andduration of the illumination. More typically, about 20 wt % of the totalweight of tile 10 is consisted of the photoluminescent particles.

The main ingredients, including the inorganic fillers, thermoplasticbinder system and the photoluminescent particles can be placed in ashearing mixer and are thoroughly mixed. This ensures that thephotoluminescent particles 16 are distributed evenly throughout themixture. Optionally, non-photoluminescent color pigments can also beincorporated. The mixer heats the ingredients to about 280° F. Theheated mixture is discharged from the mixer and passes through a rollmill to form a blanket. The blanket is about 200 mils (0.2 inch) thick.More typically, the blanket is about 80-130 mils (0.1 inch) thick forcommercial grade tiles. The blanket is then heated and rolled severaltimes to partially cross-link the polymeric ingredients in thethermoplastic binder system and form a finished gauge blanket. Ifdesired, a wax or urethane overcoating or other surface treatment can beapplied. The sized and finished blanket is then transferred to a pressthat punches individual tiles 10 from the blanket.

The tiles 10 are installed in the same manner as any type of commercialfloor tile, particularly VCT tiles. This enables a photoluminescentbackup system to be installed simultaneously with floor installation,without additional labor.

The photoluminescent particles 16 on the top surface 12 of the tile 10absorb light from the ambient lighting, including sunlight, fluorescentor incandescent lightings. During a blackout, they are capable ofreleasing the light and supplement backup lighting. Less than 1 hour oflight exposure is typically sufficient to charge the photoluminescentparticles.

FIGS. 4 a and 4 b show a second embodiment of the present inventionwherein photoluminescent chips 116 are embedded evenly throughout a tilebase 18 to provide a photoluminescent tile 110.

“Photoluminescent chips”, as used here, refer to small pieces ofaggregates of photoluminescent particles. For purpose of this invention,there are essentially two types of photoluminescent chips. In oneaspect, the photoluminescent chips are ground-up or crushedphotoluminescent tile 10. Each chip therefore has the same compositionof a photoluminescent tile according to the first embodiment of theinvention. The photoluminescent chips are typically about 2-20 mils indimensions. More typically, they are about 2-10 mils in dimensions. Inanother aspect, the photoluminescent chips comprises onlyphotoluminescent particles and the thermoplastic binder system, noinorganic filler is present. In this aspect, the photoluminescentparticles comprise about 50-95 wt % of the weight of each chip, whereasthe thermoplastic binder system comprise about 5-50 wt % of the weightof each chip.

The photoluminescent chips are mixed thoroughly with a tile basecomposition, i.e., the inorganic filler and the thermoplastic bindersystem, to form a photoluminescent tile. Typically, the chips are addedinto a heated, well-mixed tile base composition. The chips are thenmixed for a short period of time to ensure that the chips are disbursedthroughout the tile base.

Typically, the photoluminescent chips comprise about {fraction(1/5)}-{fraction (3/4)} of the total weight of the tile 110. Moretypically, the photoluminescent chips comprise about ⅓ of the entiretile 110 to ensure sufficient amount of the chips on the top surface ofthe tile.

In addition to providing the illumination, the photoluminescent chipsalso endow the tile 110 with varied appearances such as the striatedpatterns (shown in FIG. 4 a) and the marbled patterns (shown in FIG. 4b). The different appearances in patterns can be controlled by theprocesses by which the photoluminescent chips are mixed with the tilebase composition. More specifically, the duration of the mixing of thechips with the tile base composition determines the appearance of thefinished tile. The longer the chips are mixed with the heated tile basecomposition, the softer and more pliable the chips become and the easierthey can be reshaped when the tile blanket is rolled out. For example,when the photoluminescent chips are mixed together with the tile basecomposition at high temperature for 80 seconds, the chips become morepliable due to the partial melting of the thermoplastic binder whichsoftens the formerly rigid and cross-linked structure. When the tilemixture is rolled out into a blanket, the chips embedded therein arereshaped and tend to be elongated, hence provides the striated patternon the tile surface (FIG. 4 a). When the chips are mixed for only 40seconds, they are less likely to be radically reshaped. At the sametime, the heat is sufficient to reduce and round out the irregularitiesof the edges of each chip. The rolled out tile therefore tend to have amarbled pattern (FIG. 4 b).

Colored, non-photoluminescent pigments in the forms of powders or chips,that are common decorative additives to a tile composition can beoptionally added to the tile mix for making the photoluminescent tiles10 to enhance the diversity of the appearance of the tiles or thephotoluminescent chips made therefrom. These colored pigments arecommercially available from, for example, Bayer Chemicals and Du PontIndustry.

The photoluminescent tiles according to the first and second embodimentshave the rigidity and mechanical strength that meet the industrystandard. The incorporation of the photoluminescent material into thetile base enable the tiles to illuminate in the dark. Because thephotoluminescent material is disbursed throughout the tile base, freshphotoluminescent material is always available on the surface despiteheavy wears in the tiles.

The photoluminescent tiles 10 and 110 can be installed in exactly thesame manner as any commercially available tiles. As noted above, theirmechanical properties are particularly close to the non-photoluminescentvinyl resin based VCT tiles, such as those commercially available fromCongoleum Inc., Armstrong World Industry and Manington Inc. Accordingly,each photoluminescent tile typically has the same appearance of anon-photoluminescent VCT tile under normal ambient lightings. Thesephotoluminescent tiles can be combined with non-photoluminescent VCTtiles during installation to form versatile patterns or signs. A floorlaid with both the photoluminescent and non-photoluminescent tiles whichmay appear to be an uniform floor under normal lighting, will instantlyproduce a variety of glowing patterns in a dim light or completedarkness. The patterns include bond patterns, checkerboard patterns,geometric shapes, words or borders. This feature is particularly usefulin guiding people to exists in public buildings, such as hospitals,hotel lobbies or the like. It may also be used to provide decorative orentertaining patterns for venues such as dance floors, skating rinks,sidewalks and convention centers.

FIG. 5 illustrates a floor forming a portion of an escape route. Thefloor includes a number of floor tiles 10 (each shown with an “X”) andnon-photoluminescent tiles 20. The floor appears to be an uniform floorunder normal lighting. In a blackout, the tiles 10 illuminate an areasurround by the dark tiles 20. In addition to illuminating an escaperoute, the tiles 10 can be arranged to provide useful indicia. In FIG.5, the tiles 10 are arranged to define an arrow indicating directionalong the escape route.

FIG. 6 further illustrates a floor in which photoluminescent tiles 10are combined with non-photoluminescent tiles 20 to form an interlockedherringbone patter. Likewise, photoluminescent tiles 110 can be combinedwith the non-photoluminescent tiles 20 in the same manner as illustratedin FIGS. 5-6.

Photoluminescent Tiles having Wear Layers

Because photoluminescent material are costly, the incorporation of whichthroughout the entire tile base may become economically unfeasible inspite of the incremental benefit of having fresh photoluminescentmaterial always available on the surface of even severely worn tiles.Thus, the present invention further provides photoluminescent tileshaving a wear layer, wherein, a photoluminescent material is presentonly in the wear layer. These photoluminescent tiles can withstandnormal wear and tears within the limitation of the thickness of the wearlayer to ensure a reliable and continuous illumination during the tile'suseful life. The cost of these tiles, due to the reduction of thematerial cost associated with the photoluminescent particles, becomemore reasonable and comparable to other specialty tiles.

The term “wear layer”, as used herein, refers broadly to a layer thatconstitutes an upper portion of a photoluminescent tile of the presentinvention. In detail, the wear layer is, with or without further surfacetreatment, the portion of the photoluminescent tile that is exposed tothe ambient environment after installation. The wear layer comprises atile base composition having a photoluminescent material, includingphotoluminescent particles and photoluminescent chips, disbursedthroughout. As will be discussed in more details below, the wear layercan be a layer that is processed separately and affixed to anon-photoluminescent substrate, such as a tile base. Alternatively, thewear layer is an integral part of the tile and is formed by pressingphotoluminescent material into a depth within a tile base.

Thus, in a third embodiment, the present invention provides aphotoluminescent tile comprising a tile base bonded with a wear layer,wherein the wear layer including photoluminescent particles disbursedevenly throughout. As shown in FIG. 7 (not drawn to scale), a wear layer220 overlies a substrate 212 to provide a photoluminescent tile 210.Photoluminescent particles 16 are only present in the wear layer 220.Essentially, this type of photoluminescent tile combines anon-photoluminescent substrate with the photoluminescent tile of FIGS.1-3 to provide a rigid tile having photoluminescent particles containedonly in the upper portion of the finished tile. Optionally, a topsurface of the wear layer can be treated with a transparent overcoating214.

The composition of the wear layer 220 is the same as thephotoluminescent tile as described in association with FIGS. 1-3. Thewear layer 220 thus comprises the tile base 18 and photoluminescentparticles 16. The substrate 212 can be a non-photoluminescent tile base,which composition is as defined and described above.

Because the wear layer and the tile base are processed separately, theirrespective compositions and thicknesses can be controlled and customizedwhile taking into consideration of factors such as but not limited to:the overall thickness of the finished tile, any specific requirement forthe thickness of the wear layer, any cosmetic or special surfacetreatment for the wear layer. Typically, about {fraction (1/10)} to ⅘ ofthe entire thickness of the finished photoluminescent tile can be thewear layer. More typically for commercial tiles of 80-100 mils inoverall thickness, the wear layer is about 10-20 mils thick.

The wear layer and the tile base are bonded or fused together byheating, calendaring or any other methods generally known to one skilledin the art. Although the tile base and the wear layer are processed andmanufactured independently of each other before they are fused together,it is advantageous that they possess similar degree of rigidity toensure the structural integrity of the finished tile throughout itsuseful life.

A forth embodiment of the present invention provides a photoluminescenttile comprising a tile base bonded with a wear layer, wherein the wearlayer including photoluminescent chips disbursed evenly throughout. Asshown in FIG. 8 (not drawn to scale), a wear layer 320 overlies asubstrate 312 to provide a photoluminescent tile 310. Photoluminescentchips 116 are only present in the wear layer 320. Essentially, this typeof photoluminescent tile combines a non-photoluminescent substrate withthe photoluminescent tiles of FIGS. 4 a and 4 b to provide a rigid tilehaving photoluminescent chips contained only in the upper portion,namely the wear layer, of the finished tile.

The composition of the wear layer is the same as the photoluminescenttile as described in association with FIGS. 4 a and 4 b. The compositionof the substrate can be that of a tile base and is as defined anddescribed above.

Because the wear layer and the tile base are processed separately, theirrespective compositions and thicknesses can be controlled and customizedwhile taking into consideration of factors such as but not limited to:the overall thickness of the finished tile, the dimension of thephotoluminescent chips, any specific requirement for the thickness ofthe wear layer, any cosmetic or special surface treatment for the wearlayer. For example, the composition of the wear layer can be separatelyselected to provide high mechanical strength for long lasting usage whenexposed to foot traffic or other external environment. Typically, about{fraction (1/10)} to ⅘ of the entire thickness of the finishedphotoluminescent tile can be the wear layer. More typically forcommercial tiles of 100 mils in overall thickness, the wear layer isabout 10-20 mils thick.

The wear layer and the tile base are bonded or fused together byheating, calendaring or any other methods generally known to one skilledin the art. Although the tile base and the wear layer are processed andmanufactured independently of each other before they are fused together,it is advantageous that they possess similar degree of rigidity toensure the structural integrity of the finished tile throughout itsuseful life.

A fifth embodiment of the present invention provide a photoluminescenttile comprising a tile base having a top surface, and photoluminescentparticles embedded into a depth within the tile base thereby providing awear layer, the photoluminescent particles covering at least 10% of thetop surface of the tile.

The composition of the tile base is as described above. As shown in FIG.9 (not drawn to scale), in a photoluminescent tile 410, thephotoluminescent particles 16 are embedded into a depth of D within thetile base 18. The photoluminescent particles 16 are on or near the topsurface 430, thus forming a wear layer 420.

Unlike the photoluminescent tiles having wear layers separatelyprocessed before being affixed to a non-photoluminescent substrate, thisembodiment provides a wear layer that does not have a well-definedboundary where the wear layer ends within the tile base. However, thisdoes not prove to be a drawback. Depends on the thickness of thephotoluminescent particles deposited on the surface of the tile blanket,the depth D can be typically controlled at between 2-20 mils, and moretypically between 2-10 mils, which are within the satisfactory thicknessfor a wear layer.

To form the photoluminescent tile 410, the tile base composition aremixed and formed into a blanket as in making a non-photoluminescenttile. Before the blanket is cooled off, the photoluminescent particles16 are dusted or otherwise distributed on the top surface of theblanket. The dusted blanket is rolled to embed and disburse theparticles into a depth of D within the upper portion of the blanket.Optionally, non-photoluminescent color chips can be dusted and embeddedinto the tile base along with the photoluminescent particles 16. Thefinished gauge blanket can be then optionally subjected to a surfacetreatment and the tiles are punched from the blanket as previouslydescribed. Depending on the amount of the photoluminescent coveragedesired on the top surface of the tile and the thickness of the wearlayer, the photoluminescent particles can be dusted on the entiresurface or only in space-apart areas. The patterns of the particledistributions also provide versatility to the surface appearances.

Advantageously, in this embodiment, the wear layer is not technically aseparate layer from the tile base as to require an additional step ofrolling out a separate photoluminescent tile blanket. Rather, the wearlayer is formed during the same process of forming the tile baseblanket. As a result, both the labor and material cost are reduced.

A sixth embodiment of the present invention provides a photoluminescenttile comprises a tile base having a top surface, and photoluminescentchips embedded into a depth within the tile base thereby providing awear layer, the photoluminescent chips covering at least 10% of the topsurface of the tile.

The composition of the tile base is as described above and thecomposition of the photoluminescent chips are as previously defined. Asshown in FIG. 10, in a photoluminescent tile 510, photoluminescent chips116 are embedded into a depth of D within a tile base 18. Thephotoluminescent particles 116 are on or near the top surface 530, thusforming a wear layer 520.

Similar to the previous embodiment, this type of tile does not require aseparate process of forming a discrete wear layer. Rather, thephotoluminescent chips are sprinkled onto the top surface of a tile baseblanket before it is cooled off. The chips are then pressed and rolledinto the tile base thus forming a wear layer. Optionally,non-photoluminescent color chips can be embedded into the tile basealong with the photoluminescent chips.

Depends on the amount and dimension of the photoluminescent chipssprinkled on top of a tile blanket, the depth D can be typicallycontrolled at between 2-20 mils, and more typically between 2-10 mils.

The present invention is now illustrated by the following non-limitingexamples.

EXAMPLES Example 1

A representative photoluminescent tile 10 has the following formulation,in which the photoluminescent particles constitute 20 wt % of the totalweight of the finished tile. TABLE 1 Ingredients Amount (pounds)inorganic fillers ground limestone (60 mesh) 163 ground limestone (80mesh) 195 thermoplastic binder acetate vinyl resin 17 system stabilizer1 vinyl resin 23 plasticizer 16 photoluminescent photoluminescentparticles 106 material

Example 2

In the process of tile production, a main source of waste tilesoriginates from the remainder of a tile blanket after the tiles havebeen punched out. Other sources include defective or broken tiles off aproduction line. These waste tiles are almost invariably recycled andare referred in the industry as “line remix” or “line dust”. Aspreviously discussed, because the thermoplastic binder system isthermally reversible, the waste tiles can be reincorporated into asubsequent production line. When they are mixed with the freshingredients at high temperature in the next production, the recycledtiles soften and become miscible with the other ingredients due to thedisintegration of the polymeric cross-linking network. The mixture willthen be processed into a new tile blanket.

Because the recycled tiles often contain photoluminescent particles froma previous batch of tile-production, a reformulation of the productionline into which the recycled tiles are incorporated may be warranted.The principle concern is one of economics. Photoluminescent particlesare costly and it is desirable to only use an amount that is necessaryto provide sufficient illumination. For example, it has been found thatwhen the weight of the photoluminescent particles is about 20 wt % ofthe total tile weight, as represented by the formulation in Example 1,there is sufficient amount on the tile surface to ensure an enduringillumination. When the recycled tiles from the production line ofExample 1 is reincorporated into a subsequent production line, if theoverall weight remains the same, less than 106 pounds ofphotoluminescent material is needed to produce photoluminescent tileshaving 20 wt % photoluminescent material.

Table 2 below illustrates a new formulation, wherein the overall weightof the material remains the same as that in Example 1. TABLE 2Ingredients Amount (pounds) inorganic fillers ground limestone (60 mesh)122 ground limestone (80 mesh) 154 thermoplastic binder acetate vinylresin 17 system stabilizer 1 vinyl resin 23 plasticizer 16 recycledtiles* line remix 65 line dust 37 photoluminescent photoluminescentparticles 86 material*The tiles are recycled from the production line of Example 1 or Example2.

All of the above U.S. patents, U.S. patent application publications,U.S. patent applications, foreign patents, foreign patent applicationsand non-patent publications referred to in this specification and/orlisted in the Application Data Sheet, are incorporated herein byreference, in their entirety.

From the foregoing, it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

1. A rigid photoluminescent tile comprising: a tile base having a topsurface; a thermoplastic binder system within said tile base, thethermoplastic binder system being 5-50 wt % of the total weight of thetile; a non-transparent inorganic filler within said tile base; and aphotoluminescent material within the tile base and being exposed on saidtop surface of said tile base, wherein the combined weight of theinorganic filler and the photoluminescent material is 50-95 wt % of thetotal weight of the tile.
 2. The photoluminescent tile of claim 1wherein the combined weight of the inorganic filler and thephotoluminescent material forms 60-90 wt % of the total weight of thetile.
 3. The photoluminescent tile of claim 1 wherein the combinedweight of the inorganic filler and the photoluminescent material forms70-85 wt % of the total weight of the tile.
 4. The photoluminescent tileof claim 1 wherein the inorganic filler is limestone.
 5. Thephotoluminescent tile of claim 1 wherein the photoluminescent materialis distributed evenly throughout the entire tile base.
 6. Thephotoluminescent tile of claim 5 wherein the photoluminescent materialcomprises a plurality of fine photoluminescent particles.
 7. Thephotoluminescent tile of claim 6 wherein the photoluminescent particlescomprise 10-90 wt % of the total weight of the tile.
 8. Thephotoluminescent tile of claim 7 wherein the photoluminescent particlescomprise about 20 wt % of the total weight of the tile.
 9. Thephotoluminescent tile of claim 5 wherein the photoluminescent materialcomprises a plurality of photoluminescent chips, each of saidphotoluminescent chips includes a thermoplastic binder system andphotoluminescent particles, wherein the thermoplastic binder system is5-50 wt % of the weight of each individual chip. 10 The photoluminescenttile of claim 9 wherein the photoluminescent chips further include anon-transparent inorganic filler, and the combined weight of theinorganic filler and the photoluminescent particles is 50-95 wt % of theweight of each individual chip.
 11. The photoluminescent tile of claim 9wherein the photoluminescent chips further include a plurality ofnon-photoluminescent color pigments.
 12. The photoluminescent tile ofclaim 9 wherein the photoluminescent chips are about 2-20 mils indimension.
 13. The photoluminescent tile of claim 9 wherein thephotoluminescent chips are about 2-10 mils in dimension.
 14. Thephotoluminescent tile of claim 9 wherein the photoluminescent chipscomprise about ¼ to ¾ of the total weight of the tile.
 15. Thephotoluminescent tile of claim 14 wherein the photoluminescent chipscomprise about ⅓ of the total weight of the tile.
 16. Thephotoluminescent tile of claim 9 wherein the photoluminescent particlesare 10-90 wt % of the weight of each individual photoluminescent chip.17. The photoluminescent tile of claim 16 wherein the photoluminescentparticles is about 20 wt % of the weight of each individualphotoluminescent chip.
 18. The photoluminescent tile of claim 1 thephotoluminescent material is embedded in a portion of the tile base onand near the top surface to form a wear layer.
 19. The photoluminescenttile of claim 18 wherein said photoluminescent material covering atleast 10% of the surface area on the top surface.
 20. Thephotoluminescent tile of claim 18 wherein the wear layer is 10-20% ofthe overall thickness of the tile.
 21. The photoluminescent tile ofclaim 20 wherein the wear layer is 2-20 mils in thickness.
 22. Thephotoluminescent tile of claim 20 wherein the wear layer is 2-10 mils inthickness.
 23. The photoluminescent tile of claim 18 wherein thephotoluminescent material comprises a plurality fine photoluminescentparticles.
 24. The photoluminescent tile of claim 18 wherein thephotoluminescent material comprises said photoluminescent chips includea thermoplastic binder system and photoluminescent particles, whereinthe thermoplastic binder system comprises 5-50 wt % of the weight ofeach chip.
 25. The photoluminescent tile of claim 24 wherein thephotoluminescent chips further comprises a non-transparent inorganicfiller and the combined weight of the inorganic filler and thephotoluminescent particles is 50-95 wt % of the weight of each chip. 26.The photoluminescent tile of claim 24 wherein the photoluminescent chipsare about 2-20 mils in dimension.
 27. The photoluminescent tile of claim24 wherein the photoluminescent chips are about 2-10 mils in dimension.28. The photoluminescent tile of claim 24 wherein the photoluminescentparticles comprise about 10-90 wt % of the weight of each individualphotoluminescent chip.
 29. The photoluminescent tile of claim 28 whereinthe photoluminescent particles comprise about 20 wt % of the weight ofeach individual photoluminescent chip.
 30. The photoluminescent tile ofclaim 18 wherein the wear layer is a layer separately processed andlaminated on top of the non-photoluminescent tile base.
 31. Thephotoluminescent tile of claim 1 further comprising a plurality ofnon-photoluminescent color pigments.
 32. A photoluminescent tilecomprising a non-photoluminescent substrate; a wear layer having a topsurface and a bottom surface, said bottom surface being affixed to thesubstrate, a thermoplastic binder system within said wear layer, saidthermoplastic binder system being about 5-50 wt % of the total weight ofthe wear layer; a non-transparent inorganic filler within said wearlayer, a photoluminescent material within said wear layer and beingexposed on the top surface of said wear layer, wherein the combinedweight of the inorganic filler and the photoluminescent material isabout 50-95 wt % of the total weight of the wear layer.
 33. Thephotoluminescent tile of claim 32 wherein the substrate is anon-photoluminescent tile base comprising, of the total weight of thetile base, 5-50 wt % thermoplastic binder system and 50-95 wt %non-transparent inorganic filler.
 34. The photoluminescent tile of claim32 wherein the combined weight of the inorganic filler and thephotoluminescent material is 60-90 wt % of the total weight of the wearlayer.
 35. The photoluminescent tile of claim 32 wherein the combinedweight of the inorganic filler and the photoluminescent material is70-85 wt % of the total weight of the wear layer.
 36. Thephotoluminescent tile of claim 32 wherein the photoluminescent materialcomprises a plurality of fine photoluminescent particles.
 37. Thephotoluminescent tile of claim 36 wherein the photoluminescent particlescomprise 10-90 wt % of the total weight of the wear layer.
 38. Thephotoluminescent tile of claim 37 wherein the photoluminescent particlescomprise about 20 wt % of the total weight of the wear layer
 39. Thephotoluminescent tile of claim 32 wherein the photoluminescent materialcomprises a plurality of photoluminescent chips, said photoluminescentchips include a thermoplastic binder system and photoluminescentparticles, wherein the thermoplastic binder system comprises about 5-50wt % of the weight of each individual chip.
 40. The photoluminescenttile of claim 39 wherein the photoluminescent chips further comprise anon-transparent inorganic filler, wherein the combined weight of theinorganic filler and the photoluminescent particles forms 50-95 wt % ofthe weight of each chip.
 41. The photoluminescent tile of claim 39wherein the photoluminescent chips are about 2-20 mils in dimension. 42.The photoluminescent tile of claim 39 wherein the photoluminescent chipsare about 2-10 mils in dimension.
 43. The photoluminescent tile of claim39 wherein the photoluminescent chips comprise about ¼ to ¾ of the totalweight of the wear layer.
 44. The photoluminescent tile of claim 43wherein the photoluminescent chips comprise about ⅓ of the total weightof the wear layer.
 45. The photoluminescent tile of claim 39 wherein thephotoluminescent particles comprise about 10-90 wt % of the weight ofeach individual photoluminescent chip.
 46. The photoluminescent tile ofclaim 45 wherein the photoluminescent particles comprise about 20 wt %of the weight of each individual photoluminescent chip.
 47. Thephotoluminescent tile of claim 38 further comprising a plurality ofnon-photoluminescent color pigments.
 48. A floor comprising: a pluralityof rigid photoluminescent tiles, said photoluminescent tiles including atile base having a top surface, a thermoplastic binder system withinsaid tile base, the thermoplastic binder system being 5-50 wt % of thetotal weight of the tile; a non-transparent inorganic filler within saidtile base; and a photoluminescent material within the tile base andbeing exposed on said top surface of said tile base, wherein thecombined weight of the inorganic filler and the photoluminescentmaterial is 50-95 wt % of the total weight of the tile; and a pluralityof rigid non-photoluminescent tile.
 49. The floor of claim 48 whereinthe photoluminescent tiles form a pattern.